1. Field of the Invention
The general field of the present invention is that of combination padlocks possessing a rigid, sliding, shackle, more particularly combination padlocks possessing a rigid, sliding, shackle further possessing tumbler rings and most specifically combination padlocks possessing a rigid, sliding, shackle further possessing a shackle and tumbler rings which are both removable from the padlock in order to permit permutation of the combination code utilized to open the lock.
2. General Background
Combination padlocks possessing a rigid, sliding, removable shackle and tumbler rings removable therefrom in order to permit permutation of the combination code are considered to be characterized by the utilization of a sleeve removable from the tumbler ring which has numerical indicia fixed peripherally and which may be rotated with respect to the tumbler ring in order to change the number corresponding to the rotational position of the tumbler ring which enables opening.
This arrangement enables selection of any desired numerical combination code comprised of the number of digits determined by the number of tumbler rings utilized. It is considered that transposition of tumbler rings sequentially enables permutation of the combination code for opening without use of numerically marked sleeves removable from the tumbler rings but that this only enables n factorial combination codes for opening. If, for example, four tumbler rings are utilized than 4.times.3.times.2=24 combination codes for opening are enabled while the use of rotational variable sleeves upon four tumbler rings allows 10.sup.4 =10,000 possible combination codes for opening, assuming that all ten digits, i.e. 0-9, are present on each sleeve. The relative merit to being able to interpose tumbler rings as opposed to rotationally varying indicia position is hence considered small.
It is considered that numerical codes are more difficult to remember than words or combinations of letters, i.e. alphabetic characters, but that the use of tumbler rings or sleeves rotationally variable with respect to the tumbler rings cannot realistically contain all the letters of an alphabet. If each letter is given one quarter of an inch spacing upon the periphery of the ring or sleeve a circumference of 6.5 inches or a diameter exceeding two inches is required for accommodation of the English alphabet of twenty-six letters. This is considered to be ungainly and economically infeasible for an inexpensive padlock and explicative of why such a device is generally unknown.
Lacking any known padlock possessing a rigid, slidable, removable shackle demonstrating the use of letters, much less any such padlock permitting the selection of letters upon tumbler rings removable from the padlock for the purpose of selecting a particular combination of letters for the combination code opening the padlock the review of the known prior art below is representative of combination padlocks possessing a rigid, slidable, removable shackle permitting permutation of numeric indicia.
Discussion of the Prior Art
The below listed U.S. Patents are considered to be of pertinence to the present invention.
______________________________________ U.S. Pat. No. Inventor Date Title ______________________________________ 419,553 Porter Jan 14, 1890 Permutation Padlock 494,541 Baron April 4, 1893 Permutation Padlock 595,650 Redman Dec 14, 1897 Combination Padlock 1,551,952 Hanflig Sept 1, 1925 Combination Lock Re. 16,215 Tobler Nov 24, 1925 Combination Lock 1,924,987 Furino Aug 29, 1933 Combination Lock 4,615,191 Grandy Oct 7, 1986 Barrel Combination Lock 5,540,065 Wyers July 30, 1996 Locking Device ______________________________________
All of the patents listed above disclose combination padlocks with a rigid, sliding, removable shackle which further permits changing of the combination code utilized. Two broad groups are recognized, six earlier patents encompassing the years 1890-1933 and two recent patents issued in 1986 and 1996. The early patents cited may be considered as exhaustive of the variations upon a single basic structure wherein the shackle is retained by dial type rings in any position other than that aligning interior kerfs to permit shackle removal which action is necessary for removal and interposition of the rings permitting change of the combination code.
Porter engages both equal length legs of the shackle with a plurality of rings rotating about a cylindrical core which possesses a top central bolt to which a cap, bored through for each leg of the shackle, is attached to trap the rings. Baron uses rings mostly enclosed in a cylinder about one shank of the shackle mounted about an exteriorly splined internal sleeve using a notched interior rib which may be set in the bifurcated groove separating adjacent splines on the internal sleeve to permit rotational permutation. A leaf spring biases the sleeve outward to maintain the position of the rings after removal of the shank. Redman uses kerfed rings about either shank of the shackle each positioned rotationally and fixed to the shank by means of a set screw. The dial rings bearing external indicia are internally keyed and the keys align with the kerfs in the open position.
Hanflig uses a vertical stack of internally and externally kerfed discs inside the casing between the two legs of the shackle, each disc having a peripheral pattern of holes normal the disc faces into which pins are located extending either upward or downward. A bottom dial integral to a central keyed shaft is used to turn the discs in a sequence of opposed rotations to align the external kerfs for opening. Tobler uses central rings with opposed notches and slots and a stud protruding into an opening through the cylindrical casing which enables rotation of the ring through an arc in a direction aligning the notch determined by the position of the opposed groove which is changed by flipping the ring. The rings may be interposed and flipped to change the sequence of ring positioning which opens the lock. Furino uses an exposed vertical stack of dial rings each held by a leaf spring rotationally with respect to an externally keyed internal "locking ring". Partial displacement of the shackle while in the open position holds the locking rings in place thus permitting rotation of the dial rings relative to the locking rings.
The two more recent references cited, Grandy and Wyers, both disclose combination locks with rings engaging "clutches" about a central cylinder member. The rings may be rotated with respect to the clutches and interposed to permit setting of a new code. Both use caps to retain the assemblies which are held place by use of a pin. The former uses a spring loaded pin which cannot be pushed downward when the shackle is in place. The latter uses a simple pin pressure fitted into a collar which is presumedly of plastic.
Statement of Need
The above discussed prior art demonstrates a variety of means utilized to permit permutation of a combination padlock. The interposition of tumbler rings, flipping of the same, and rotational selection of the position of a dial ring utilized for opening are disclosed. It is considered to be assumed throughout the prior art that numerical indicia only are concerned as no provision is made to enable changing of the indicia upon a single dial ring; only changing all of the indicia in a fixed sequence upon a ring is utilized in the combination code determining opening. Without the ability to change the indicia upon a dial ring of a combination padlock the use of letters as indicia is considered to be severely restricted owing to the inability of changing individual indicia upon a single tumbler ring as well as to the previously discussed concern with accommodating all the letters of an alphabet upon a single ring.
It is also considered that the above discussed prior art reveals a central concern to combination padlocks with rigid, sliding, removable shackles that permit combination permutation with removal of the shackle and the tumbler rings: maintaining a given position of the rings when the shackle is removed. It is considered that the use of internal and external rings together with various other components is often more complex than is considered desirable with regard to both the number and the shape of the various components required.
It is therefore considered that a need hence exists for some means of enabling the changing of the indicia utilized upon a tumbler ring of a combination padlock in order to make the use of letters practical as indicia. A further need is recognized for a combination padlock possessing a rigid, sliding, removable shackle which allows combination permutation with removal of the shackle and the tumbler rings which maintains a given disposition of the tumbler rings when the shackle is removed which is simple, i.e. of few parts and of simply shaped parts.